Semiconductor fabrication often involves the formation of multiple semiconductor layers on top of each other. In some cases, different types of semiconductor materials may be used for different layers. For example, a type III-V semiconductor material may be formed on top of a type IV semiconductor material.
The crystal lattice of a type III-V semiconductor alternates between a type III element and a type V element, for example, gallium and arsenic respectively. It is desirable that this pattern remain consistent throughout the crystal. During epitaxial processes which are used to grow a type III-V semiconductor, certain defects may occur. Particularly, Anti-Phase Boundary (APB) defects can occur which can adversely affect the performance of circuits formed within the semiconductor layer. Therefore, it is desired to have methods of fabrication that reduce or eliminate the formation of such defects.